Imaging devices such as inkjet printers typically operate one or more printheads that are configured to eject ink for marking media. In direct marking printers, the ink is applied directly to the media, rather than to an intermediate printing surface. The media can be, for example, a surface of a continuous web of media material, a series of media sheets, or other surfaces that are desirably marked. A printhead controller typically controls the one or more printheads by generating a firing signal with reference to image data.
Two or more printheads can be mounted linearly, or in other configurations, to a support structure, to form an array of printheads. In array printing devices, printheads are arranged to extend over the print media in a cross-process direction, which is perpendicular to a direction of media movement in the plane of the media movement. A distance between the printheads and the imaging surface is carefully selected to optimize the imaging process. If the gap is too small, burnishing of the printheads can occur when the image receiving surface contacts the face of the printheads. Burnishing not only reduces the life of the printheads, but results in poor image quality, unintentional markings, and increased downtime of the printer during maintenance. If the gap is too large, image quality suffers, particularly in high speed printers, where a large gap can result in decreased accuracy of the ejected drops forming the printed image. A nominal gap distance between printheads and an image receiving surface can be, for example, about 1 mm or less.
In imaging devices for printing images on separate sheets of media, sheets of media are sequentially fed through the imaging device. Each media sheet has a leading edge that may be susceptible to dislocation, curling, wrinkling, or other types of distortion, and printheads in cut sheet imaging devices are at risk to burnishing and damage. While the media in continuous-feed imaging devices do not have leading edges, height distortions, such as seams and wrinkles, can be present in continuous media webs and thus also risk impacting printheads. Systems have been produced for adjusting the gap between printheads and the imaging surface, but involve interrupting the printing process, are not optimized for high-speed printing, or result in a decrease in fidelity or accuracy in the printed image.
An additional risk involves contaminant accumulating on printheads from sources such as ejected ink from other printheads, dust, particulates from the media, or the like. Dust particulates and other contaminations can clog nozzles. When printheads are in close proximity to one another, ejected ink from one printhead may splash or spray onto another. While devices have been produced that can be used to clean or wipe a printhead, such use often interrupts the printing process and involves what can be complex maintenance devices and procedures. Further, wiping mechanisms can potentially exacerbate these risks by pushing particulates into the nozzle openings.
These risks are compounded when, as in many modern imaging devices, a plurality of different printheads are included in a device. Including more printheads in an imaging device increases the chance that media distortion or contamination results in damage to one of the printheads that can negatively impact the lifespan of printheads. Therefore, systems and methods that reduce printhead damage and contamination in imaging devices operating at a high rate of speed without interrupting the printing process or impacting the quality of the printed image would be beneficial.